Method of making plastic bags



Feb. 14, 1961 L. E. CANNO 2,971,874

METHOD OF MAKING PLASTIC BAGS Filed March 14, 1960 2 Sheets-Sheet 1 I0 3I2 I30 132 we T IN V EN TOR.

Feb. 14, 1961 Filed March 14, 1960 L. E. CANNO 2,971,874 METHOD OFMAKING PLASTIC BAGS 2 Sheets-Sheet 2 INVENTOR.

ATTORNEYS 2,971,874 METHOD OF MAKING PLASTIC BAGS Leonard E. Canno, NewYork, N.Y., assignor to Equitable Paper Bag Co. Inc., Long Island City,N.Y., a corporation of New York Filed Mar. 14, 1960, Ser. No. 14,933 7Claims. (Cl. 154-83) This invention relates to the manufacture ofplastic bags and more especially bags that have a reinforcing strip atthe upper end of the bag above a zone along which the bag is sealed.

7 Plastic bags, and particularly polyethylene bags, are used as low-costcontainers, and any improvements in construction to reinforce the bag orto provide better panel space for information and advertising, must beinexpensive in order to be useful in commercial packaging.

It is an object of this invention to provide a method for making animproved plastic bag in which the plastic sheet material is folded atthe top of the bag and extended downwardly to form the front and backpanels of the bag. The method introduces ,a stiffener into the foldduring the making of the bag, and this stiffener extends down close tothe zone atwhich the front and back panels are sealed together to closethe upper end of the portion of the bag that contains the merchandise.

The invention provides a combination of steps in which the reinforcingstiffener is introduced into the fold of the bag, and punching andsealing operations are performed at times which tend not to reduce thespeed of manufacture and in which the additional operations areperformed simultaneously with others that are necessary in themanufacture of conventional bags of the type to which this inventionrelates.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like referencecharacters indicate corresponding parts in all the views: a

Figure 1 is a diagrammatic top plan view of apparatus for making plasticbags in accordance with this invention;

Figure 2 is an enlarged view showing one of the plastic bags made by themethod disclosed in Figure 1;

Figures 3 and 4 are greatly enlarged, fragmentary,

sectional views taken on the lines 3-3 and 4-4, respectively, of Figure2;

Figure 5 is an enlarged sectional view taken on the line 55 of Figure 1;and

Figure 6 is a fragmentary, along the line 6 6 of Figure 1.

Figure 1 shows a spool 10 supported by an axle 12 from bearings in aframe 14. A web 16 of plastic sheet, preferably polyethylene, is wrappedin a reel 18 on the spool 10. The web 16 is unwound from the reel 18 andadvanced, towardthe right in Figure 1, to a folder guide 20 at which theweb is folded along a longitudinal line offset slightly from the centerof the web.

Another spool 24 is supported by an axle 26 from bearings 28. A strip ofstiffener material 30, such as cardboard, is wrapped in a reel 32 on thespool 24.

This strip of stiffener 30 is withdrawn from the spool 24 and isadvanced to the folder guide 20 immediately under the web 16.

diagrammatic view taken United States Patent The web 16 is folded withone edge of the stiffener 30 along the inside of the fold, and with theweb 16 and stiffener 30 in this relation, they pass around a guide roll36 and advance horizontally to a series of work stations.

Some variation in the subsequent operations is permissible, but in thepreferred operation of the invention, the folded web 16 is firstsubjected to the operation of a perforating die 40 which leaves a row ofspaced incisions 42 through both layers of the folded web 16 and spaceda short distance beyond the edge of the stiffener 30. This perforatingdie 40 is preferably a rotary cutter secured to a shaft 44 which rotatesinbearings 46 and which is driven from a motor 48 by motion-transmittingconnections 50.

Beyond the operating station ot which the perforating die 40 is located,the folded web 16 passes under two sealers 52 which preferably applyheat to the top surface of the plastic web with sufficient intensity toheatseal the top layer of the plastic to the underlying layer along twonarrow zones 54 on opposite sides of the incised line 42, and with bothof these sealed zones 54 beyond the edge of the stiffener 3h.

The sealers 52 are held in contact with the plastic web 16 by anyconventional means and they are preferably heated electrically bycurrent supplied from trans formers 56 through conductors 5S.

After passing beyond the station at which the sealed zones 54 areformed, the folded plastic web 16 passes through a loop accumulator,best shown in Figure6. The web 16 is advanced by continuously-operatingfeed rolls 60 driven from the motor 48 through motion transmittingconnections 5t Beyond the continuously-operating feed rolls 60, thefolded Web 16 passes upwardly around a slack accumulator roller 64,supported from a fixed structure 66 by yieldable supporting means 68.The web 16 passes around the loop accumulator roller 64 and downwardlyto intermittently-operated feed rolls 70 driven from a transmission 72by a motion-transmitting connection 74. Power is supplied to thetransmission 72 from a motor 76 supplied with electric current throughspeed control means 78 in a power line 80.

The transmission 72 operates the feed rolls 70 with intermittent motioncorrelated with the operation of tools at other operating stations. Suchcorrelation with step-by-step movement of a work piece is wellunderstood in the art and no further illustration of apparatus isnecessary for a complete understanding of this invention.

The yieldable support 68 maintains a constant tension on the loop formedby passage of the web 16 around the roller 64 and this results in anupward movement of the roller 64 when the feed rolls 70 are stationary,and a downward movement of the roller 64 when the-feed rolls 70 are inoperation. The amount of web fed by the intermittently-operating feedrolls 70 must be equal to, that fed by the continuously-operating feedrolls 60 over a period of time.

Beyond the slack accumulator, the folded web 16 passes a cutter 84having a blade 86 (Figure 1) which cuts notches 88 through the fold ofthe web and for a distance substantially equal to the width of thestiffener 30. Thus the notches 88 extend close to the nearer sealed zone54, and preferably somewhat beyond the stiffener 330. This operationseyers the stiffener strip so that there are separate stiffeners 30between, successive notches 88. In the preferred operation, the edgesofthe notches 88 are preferably made with a slight degree of concavecurvature, as shown in Figure 2.

Beyond the cutter 84, the folded web passes to a punching station 90 atwhich a punch 92 makes a hole 94 adjacent to the fold.

throughthefolded web and the stiffener at a location midway betweensuccessive notches 88. This hole 94 may be a small one for the purposeof hanging the bags i1' -hohks, o'r with'largerhags it' may be ofsu'fiicientsize to receive the fingers o'f a person "carrying the bag.Where s'uchprovision' is tobe made for carrying't'he bag; two or moreholes '94rnay' be punched between successive notches 88.

The next operationonithe foldedweb is a' sealing of the layers'ofplastic along zones extending transversely of the'web. This is performedat a sealing station 96 by a hot blade 98 (Figure'fi) which comes incontact with the top surface 'ofthefolded web' across the entiretransverse width of th'ewe'b. When the invention is carried out withoutcutting'riotches'hs in the folded webQthe iblade'98 may extend acrossthefull width of the web, though 'it'can'not seal the overlyinglayersof'plastic together where the stiffener 30 is located between them Inthe construction illustrated, the blade 98 may terminate at the ends ofthe notches 88, -or it may extend across the notches. The blade 98 ispreferably heated by electricity supplied from a power '"line 100. Onestep beyond the sealing station 96, the

:folded web 16 is cut at "a shearing'station 102 having a "blade 104which cutsthe folded web to form separate bags 106 (Figure 1). Thesebags are separated from 'the folded web, as fast asthey are out, byfriction on a -conveyor 108, best shown in Figure 6.

. The blade 98 heat-seals the plastic along a zone 112 (Figure 2) whichis of substantial width,and the bags 'afe'cut apart along a shear linelldmidway across the -heat-sealed-zone 1'1'2. This leaves each bag 106with a .heat-sealed-edge"region 116, shown in Figure 4.

-As'ekplained 'in connection with the original folding ofthe-,plastic-web 16, the fold is not made at the center of the web andthis leaves each bag with a front panel 120 formed'bythe-to'p'layer ofthe fold, and a rear panel '122 formed by the lower layer of the foldedweb, and .with'the rear panel 122 extending beyond the front panel512010 leaveaflap 124 for closing the bag after the bag -has been filledwith 'merchandise. Figure 3 shows the flap 124, in dotted lines, in itsfolded condition.

Various expedients can beused, if desired, for preventing end-wisemovement'o'f the stiffener 36' in the dipper folded end of the finishedbag. One such expedient is illustrated in Figures 1 and 5. An applicator130 is located between the spool and the spool 24. This applicatorcontains a roller 132 which is secured to an axle "134 driven'by a motor136 through motion-trans- -mitting connections 138.

The roller 132 has pro'iectionsldii at angularly-spaced "regions aroundit's-circumference. The stiffener strip 30 passes across the roller 132and the projections 14% conitacb with the sjtiifener strip St) at spacedlocations along itsilength asthe strip moveslongitudinally across thero- 1tating roller 132.

The lower partof the roller 132 dips into a well of adjhesive144, andthis adhesive is applied to-the bottom of the stiffener strip 30bycontact of the projections 14%) "withtheadvancing strip. This producesspots 146 (Figtires 1 and 2) of adhesive along'the stiffener strip 39;and-this adhesive is of a nature which sticks to the inner face of thepolyethylene web which confronts the spots 146 in the finished bag. Manyother expedients for pre- "venting end-wise movement of the stiffener 3Gin the fineished bag can be used. The roller 14%) can be used torpunch'holes instead of applying adhesive; and the plasitic materialareas confronting one another through the "-holes'can be'heat sealed toone another.

the regions thatare sealed'tran'sverselyof the folded web.

length of the Weband'strip' mew-ah said The. preferred embodiment of theinvention hasbeen illustrated and described, but changes andmodifications can be made, and some features can be used in differentcombinations Without departing from the invention as defined in theclaims.

What is claimed is:

1. The method of makin'g' plastic bags, each of which has a topcompartment sealed on from'the remainder of the bag and withareinforcing strip enclosed in the sealed-off compartment; "which method"comprises fadvancing a' web of plastic 'film from .a su'pply source andsimultaneously advancing a continuous length of the reinforcing stripwith the film w ebffolding the web of plastic film with --the strip-within the fold, sealing confronting faces of'the web to one' anotherimmediately below the strip to form, within the fold, a compartmentenclosing the strip and extending lengthwise of the strip,

also sealing the confronting faces of the web together at regions spacedfrom 'one another lengthwise of the regions extending transversely ofthe folded web, and severing the web at said regions across the fullwidthof the web and through the strip to form separate bags.

2. The method of making plastic bagsas descrihed in claim 1 and in whichholes are "punched "through the folded film and strip 'at regions spacedalong the length of the strip and at a location that is substantiallymidway betweenthe'parts of the web and strip that are severed to makethe separate bags.

3. The method of making plastic bags as described in claim 1 and inwhich the confronting faces of the web are sealed together transverselyofthe folded web 'by applying heat to the' web acrossthefull'widththereof including a portion of the web where the strip isbetween the confronting facesof the web, said strip serving as a spacerto preventthe plastic from sealing at the end of the compartment.

4. The method of making plastic bags as described in claim 1 and inwhich sections of the folded plastic and the strip are severed from theremainder of'the web' and strip at regionsalong the length of the webspaced by the width of the separate bags, each severed section extendingfrom the folded edge to the inner edge of the strip at the region of thelengthwise extending seal, and each of said severed sections being ataloca'tion at the end of 5. The method of making plastic bags asdescribed in claim 1 and in which the strip is treated as spaced-regionsaiong its length, priorto the folding 'of the plastic over the strip, tomake bonding areas where the strip is held against end-wise movementwith respect to the compart ment in the finished bag.

I 6. The method of making plastic bags as described-in claim 5 and inwhich the treatmentof the strip constitutes at spotting of at least oneside of the strip with an adhesive that bonds to the plastic material-ofthe web.

7. The method of making plastic bags as described in claim 1 and inwhich the method includes punching holes in the strip before it isenclosed in the fold of the Web, and anchoring the strip againstend-wise movement in the finished bag by bonding together the faces ofthe web that confront one another through the hole punched in the stripbefore the stripis enclosed in the web.

References Qited in the tile of this patent UNITED STATES PATENTS

1. THE METHOD OF MAKING PLASTIC BAGS, EACH OF WHICH HAS A TOPCOMPARTMENT SEALED OFF FROM THE REMAINDER OF THE BAG AND WITH AREINFORCING STRIP ENCLOSED IN THE SEALED-OFF COMPARTMENT, WHICH METHODCOMPRISES ADVANCING A WEB OF PLASTIC FILM FROM A SUPPLY SOURCE ANDSIMULTANEOUSLY ADVANCING A CONTINUOUS LENGTH OF THE REINFORCING STRIPWITH THE FILM WEB, FOLDING THE WEB OF PLASTIC FILM WITH THE STRIP WITHINTHE FOLD, SEALING CONFRONTING FACES OF THE WEB TO ONE ANOTHERIMMEDIATELY BELOW THE STRIP TO FORM, WITHIN THE FOLD, A COMPARTMENTENCLOSING THE STRIP AND EXTENDING LENGTHWISE OF THE STRIP, ALSO SEALINGTHE CONFRONTING FACES OF THE WEB TOGETHER AT REGIONS SPACED FROM ONEANOTHER LENGTHWISE OF THE LENGTH OF THE WEB AND STRIP AND WITH SAIDREGIONS EXTENDING TRANSVERSELY OF THE FOLDED WEB, AND SEVERING THE WEBAT SAID REGIONS ACROSS THE FULL WIDTH OF THE WEB AND THROUGH THE STRIPTO FORM SEPARATE BAGS.